Coloured scanning electron micrograph (SEM) of reindeer lichen (Cladonia rangiferina) revealing detailed thallus structure, branching morphology, and surface texture. Reindeer lichen thrives in cold and arid environments. It is characterized by a symbiotic relationship between fungal and algal components, which is critical for the lichens photosynthesis and nutrient uptake. Reindeer lichen is a vital food source for caribou and reindeer, and plays a significant ecological role in soil formation and nutrient cycling. It is notable for its extremely slow growth rate, often less than 5 millimeters per year, making it vulnerable to overgrazing and environmental changes. Magnification: x155 when printed 10 centimeters wide.